Delaware Aqueduct Origin, New York

Part of the water-supply system for New York City, the 13.5 foot diameter Delaware Aqueduct was completed in 1944 after seven years of construction. It connects the Rondout Reservoir, which near Ellenville, to the Hillview Reservoir, in Yonkers, carrying around 50% of New York City’s water. At 85 miles, it is said to be the longest water tunnel in the world. The Rondout Reservoir is the final collection point for water from the Catskill and Delaware collection basins and reservoirs, which spill into it through the East Delaware and West Delaware tunnels, at the reservoir's northern end.